Extended Gateway Structure Export in sFlow Records
This topic describes the enhancement to sFlow on Junos OS Evolved that enables the export of the extended gateway structure, providing detailed BGP next-hop and AS information for improved network monitoring.
The extended gateway structure in sFlow records on Junos OS Evolved significantly improves network monitoring and visibility by exporting detailed BGP next-hop and autonomous system (AS) information, including AS path and communities.
The sFlow functionality is managed by the sflowapp application, replacing the legacy sflowd daemon. This transition improves scalability and integrates BGP-related data, such as AS numbers and communities into sFlow records, enabling more comprehensive network analysis.
Benefits of Extended Gateway Structure Export in sFlow Records
-
Enhanced Network Visibility: Provides detailed BGP next-hop, local AS, source AS, peer AS, AS path, communities, and local preference data, facilitating advanced traffic analysis.
-
Flexible Data Export: Allows tailored export of BGP-related data to meet specific network requirements. Allows explicit configuration of the number of AS path and community entries exported via
destination-as-pathandcommunitiescount options. -
IPv4 and IPv6 Support: Supports
inetandinet6address families, ensuring compatibility with both IPv4 and IPv6 networks for comprehensive monitoring. -
Bandwidth Optimization: Exports the extended gateway structure when relevant routes exist in the VPN routing and forwarding (VRF) table, reducing bandwidth usage.
-
Accurate Data Representation: Dynamically adjusts exported AS path and community counts to reflect actual route attributes.
-
Improved Scalability: Increases scalability and efficiency of sFlow functionality by transitioning to the sflowapp application instead of the legacy sflowd process (daemon).
Configuration
The extended gateway structure export is disabled by default due to its size and bandwidth
usage. You must configure the extended-gateway option at the [edit
protocols sflow family structure-list] hierarchy level to export an extended
gateway structure in sFlow records.
The configuration allows you to specify the number of AS paths and communities to export
using the destination-as-path count and communities count
options respectively. The default count is 8, with a range through 1 to 32. You can specify
the counts for AS paths and communities separately for IPv4 and IPv6 address families.
When enabled, the sFlow records export the following BGP-related fields in the extended gateway structure:
| Field | Description |
| next_hop | BGP next-hop IP address. For ECMP, the primary next-hop is reported. |
| as | Local AS number from BGP group, peer, or global routing instance. |
| src_as | AS number of the router advertising the source route. |
| src_peer_as | AS number of the peer router advertising the source route. |
| dst_as_path | AS path to the destination (exported only if configured explicitly). |
| communities | BGP communities associated with the route (exported only if configured explicitly). |
| localpref | Local preference for iBGP routes and eBGP routes report the default value of 100. |
If no active source or destination route exists for a sampled packet in the relevant VRF, the extended gateway structure is not exported. For static routes, local AS and local preference values are exported as zero.
Sample CLI Configuration
protocols {
sflow {
family inet {
structure-list {
extended-gateway {
destination-as-path {
count 8;
}
communities {
count 8;
}
}
}
}
family inet6 {
structure-list {
extended-gateway {
destination-as-path {
count 8;
}
communities {
count 8;
}
}
}
}
}
}